JPH03232694A - Air hoist - Google Patents

Abstract

PURPOSE:To enable it to perform the low-speed starting of a hoist and a speed variation from high to low in a stable manner by installing a braking force regulator being interlocked with travel of a piston. CONSTITUTION:An elastic means 22, gradually warming a pressing body when a piston 21 shifts in a direction where its pressing force is released, is installed in space between the pressing body 20 and the piston 21. When the piston 21 is moved in a direction where it presses the pressing body 20, energizing force, through which the elastic means 22 presses the pressing body 20 to a baking plate 2, grows larger and thereby rotation of a turning shaft 1 is braked, while when the piston 21 is moved in a direction where it release its pressure, the energizing force of the elastic means 22 pressing the pressing body 20 to the braking plate 2 is gradually decreased, allowing the rotation of the turning shaft 1. With a simple and inexpensive structure, load of a first spring 22 energizing the pressing body 20 is reducible and, what is more, the low-speed starting of an air hoist and a speed variation from high to low are all stably performable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air hoist equipped with a braking force adjustment device.

[Prior art J] Conventionally, a braking force adjustment device (brake device) for an air hoist that has a reversible rotation drive body (air motor) using compressed air (air) as a power source has a structure as shown in Fig. 6. . In FIG. 6(a), one end of the rotating shaft l is connected to an air motor (not shown), and a disk-shaped brake plate 2 is attached to the other end so as to be movable in the axial direction. The brake plate 2 includes a brake shoe 4 attached to a pressing body 3 and a housing 5.
It is held between brake shoes 6 attached to. The pressing body 3 is supported by a support member 7 so as to move along the axial direction of the rotating shaft l. A piston 8 is attached to the pressing body 3, and an air chamber A is defined between the piston 8 and the support member 7. When the pressure in the air chamber A increases, the piston 8 moves to the right in the figure, and the pressing body 3
is moved away from the brake plate 2, resulting in the state shown in FIG. 6(b). The piston 8 is urged by a spring 9 in a direction to press the brake plate 2 (to the left in the figure).

In such a brake device, air is supplied to the air chamber A between a main control valve 11 that controls air from a compressed air source (air) 10 and an air motor 12, as shown in FIG. This can be done by providing a branch circuit from the circuit, or by providing a separate circuit for the air supplied to the air motor, as shown in FIG. As described above, the structure is such that air is supplied to the air chamber A through the conduit 24 to move the piston 8, and at the same time, the pressing body 3 is separated from the brake plate 2 to release the brake.

[Problem to be solved by the invention] In the conventional technology as described above, when the air hoist is operated and stopped, the pressing body 3 must return instantly and hold the suspended load, or the air chamber It takes a short amount of time until the air in A and the air circuit is completely released (until the pressure drops to atmospheric pressure) due to the delay in pressure propagation due to air chamber A and the influence of back pressure from the air motor. Therefore, the residual pressure in the air chamber A prevents the piston 8 from returning, causing a reverse rotation of the load when hoisting is stopped and a flow of the load when hoisting is stopped.

The effect of this back pressure on the piston will be explained.

The vane type air motor 12 that rotates forward and backward is the ninth
As shown in the figure, it rotates when air is supplied from one circuit 12a, and the air that has finished its work is released from the exhaust hole 12b.
In the other circuit 12c, air is compressed by the vane and pressure is generated. When the air motor is stopped, the compressed air in the circuit 12c is exhausted to the atmosphere via the main control valve 11, or this compressed air is passed through the shuttle valve 1 which connects to the brake air circuit.
3, and becomes the back pressure of the air returning from the brake air chamber A. Although this back pressure differs depending on the air motor 12 and the main control valve 11, it is a pressure of 0.1 to 0.15 MPa, and air at this same rotational pressure remains in the brake air chamber A for a short time. This pressure prevents the piston 8 from attempting to return.

In addition, when starting the air hoist at low speed or changing the speed from high speed to low speed, it is necessary to obtain a subtle braking force by slightly separating the pressing body 3 and the brake plate 2 or bringing them into contact. There is. However, the pressure within the air motor 12 and the pressure within the circuit constantly fluctuate depending on the operating conditions of the hoist, which hinders obtaining a delicate braking force.

In the conventional structure, the pressing body 2 and the integrated piston 8 are directly affected by back pressure, so the load of the spring 9 that biases the pressing body 2 is made higher than necessary (3 to 4 times). As a result, the braking force of the flake becomes extremely large, and the moment the flake is applied, a large impact force is applied to the air hoist, putting the load in a dangerous situation.
Air hoists are subject to dangerous loads.

In addition, the relationship between air pressure, sole brake braking torque, and motor output torque is shown in Figure 3, or in order to obtain a delicate braking force using the pressing body 3 and brake plate 2, the relationship is shown in Figure 4 (b). As shown in , the piston must bring the pressing body 3 and the brake plate 2 into sliding contact by delicately increasing or decreasing the flake braking torque while the piston does not move. but,
Fluctuations in air pressure act on the pressing body instantaneously, so even if you operate the air hoist at low speed, pressure fluctuations in the circuit cause the pressing body 3 and brake plate 2 to repeatedly open and close, reducing the braking force. Because of the large fluctuations, it causes vibrations of the air hoist and the suspended load, and even when the speed is changed from high speed to low speed, the pressing body 3 instantly responds to the decrease in air pressure. , air pressure fluctuations are also taken into account, and a large braking force is applied, causing a sudden stop.

Although various improvements have been made to solve the above-mentioned problems, they are often complex in structure or expensive.

As described above, the purpose of the present invention is to reduce the load of the spring that biases the pressing body, and to reduce the load caused by the change in air pressure.
To provide a friction brake device capable of stably starting a hoist at low speed and changing speed from high speed to low speed by providing a braking force adjusting device that links changes in flake braking force with the amount of movement of a piston. It is.

Another objective is to provide a simple and inexpensive structure that solves the problems mentioned above.

[Means for Solving the Problems] In order to solve the above problems, the present invention includes: a reversible rotation drive source 12, a housing sink, a rotation shaft l rotated by the reversible rotation drive source 12, and the rotation A transmission device 15 that decelerates the rotation of the shaft l; a chain gear 16 that supports a chain 58 having a hook 17 for suspending a load and is rotated by the transmission device 15; a brake shoe fixed to the housing; A brake plate 2 attached to a rotating shaft l, a pressing body 20 that presses the brake plate 2 against the brake shoe and brakes the rotation of the rotating shaft l by frictional force, and a direction and pressure for pressing the pressing body 20. a piston 21 that is movable in the direction of releasing the pressure; and a piston 21 that is disposed between the pressing body 20 and the piston 21 and gradually loosens the pressing force of the pressing body 20 when the piston 21 moves in the direction of releasing the pressing force. Elastic means 22 were provided.

[Operation] In the present invention, when the piston 21 moves in the direction of pressing the pressing body 20, the elastic means 22 or the urging force pressing the pressing body 20 against the brake plate 2 increases, so that the rotation axis l
The rotation of the rotating shaft l is braked, and when the piston 21 moves in the direction of releasing the pressure, the elastic means 22 or the urging force that presses the pressing body 20 against the brake plate 2 gradually decreases, thereby stopping the rotation of the rotating shaft l. Allow.

[Embodiment] FIGS. 1 to 4 show a first embodiment of the present invention. As shown in FIG. 2, the air hoist has a housing sink 5, in which a compressed air port 14 is provided. Compressed air (air) @
Air is supplied from the main control valve 11.
A reversible rotation drive source (air motor) 12 is driven through the motor.

The air motor 12 drives a chain wheel 16 via a reduction gear 15 . The chain wheel 16 supports a chain 18 with a hook 17 on which a load can be suspended. The rotating shaft l connected to the air motor 12 is connected to a braking force adjustment device (
flake device) 19.

This flake device 19 is shown in Figure wS1. Figure 1(a)
As shown in the figure, a disc-shaped brake plate 2 is attached to a rotating shaft l connected to an air motor 12 that uses compressed air as a power source.
It is mounted so as to be movable in the axial direction and rotates along with the rotation axis. The brake plate 2 is held between a brake shoe 4 attached to a pressing body 20 and a brake shoe 6 attached to a housing 5. The pressing body 2o is provided with a cylindrical portion 20a on the side opposite to the side to which the brake shoe 4 is attached, and this cylindrical portion 20a is formed in a through hole provided in the support member 7 fixed to the housing sink 5. 7
a, and is supported by the support member 7 so as to move along the axial direction of the rotating shaft l. Cylindrical part 2 of pressing body 2o
A hole 21a provided in the piston 21 fits into the hole 0a, and the piston 21 can move in the axial direction relative to the pressing body 2o. The cylindrical portion 20a of the pressing body 20 is provided with a hole 20b, and a first elastic means is provided in the hole 20b.
A spring 22 is arranged, and this first spring 22 urges the pressing body 2o in the direction of the brake plate 2 (in the opposite direction to the arrow B in the figure) by the reaction force of the piston 21. The outer peripheral part 21b of the piston 21 is slidably fitted into the inner peripheral part 23a of a cylinder member 23 fixed to the housing 5. Inner peripheral part 23a of cylinder member 23, pressing body 2
An air chamber A is defined by the cylindrical portion 20a of 0, the support member 7, and the piston 21. Air is supplied to the air chamber A from an air circuit via a conduit 24 provided in the house sink 5. The piston 21 is provided with a hole 21c having a smaller diameter than the hole 21a, and this hole 21c and the pressing body 2
A bolt 25 passes through the hole 20b, and the bolt 25 is fixed to the pressing body 20.

Next, when the air hoist is operated, the plowing of each part is performed as shown in FIG. The splinter 9 is bent and moved in the direction of arrow B. The piston 21 and the second spring 9 form a pressure sensing part that moves a distance determined by the magnitude of the pressure, and the movement of the piston 21 weakens the load of the first spring 22 that urges the pressing body 20. The piston 21 and the first spring 22 form a braking force adjusting device in conjunction with the above-mentioned pressure detecting section, since the piston 21 and the first spring 22 function to increase or increase the braking force.

Furthermore, the load of the first spring 22 is set to be zero N before the piston 21 reaches its movement limit,
After the load reaches zero N, the pressing body 21 is not biased by the first spring 22.

The state becomes a free state as shown in FIG. 1(b).

Further, when the piston 21 moves, the piston 21 comes into contact with the head of the bolt 25 and moves together with the pressing body 20, breaking the frictional contact between the brake plate 2 and the brake shoe 4.6 as shown in FIG. S1 (c).

Next, a second embodiment according to the present invention is shown in FIG.

Since the brake shoes 4 fixed to the pressing body 20 wear out with use, the mounting height of the first splinter 22 that biases the pressing body 20 is increased, and the load of the first spring 22 is reduced. Therefore, if there is not enough braking force, it is necessary to correct the load on the first spring 22 to keep it constant.

FIG. 5 shows a brake shoe 4 with a structure added with a function to correct the load of the first spring 22 that urges the pressing body 20.
If the pressure body 20 moves in the direction that reduces the load on the first spring 22 (leftward in the figure) due to wear, the bolt 28 that is threaded into the nut 26 and abuts against the washer 27 can be turned counterclockwise. , the nut 26 is placed along the pin 29 in the first
Since the spring 22 is moved in the direction in which it is pressed (leftward in the figure), it becomes possible to correct the load on the first spring 22, and the nut 26, bolt 28, pin 29, and washer 27 described above have a braking force. forming a correction device;

The adjustment method is to turn the bolt 28 counterclockwise (left), bring the tip 26a of the nut 26 into contact with the pressing body 20, and then turn the bolt 28 counterclockwise (right) in advance. By turning it back a certain amount, the first spring 22
The installation can be done by keeping the height constant.

In this structure, the first spwank 2 that urges the pressing body 20
There is no mechanism for separating the pressing body 20 from the brake plate 2 after the load of 2 reaches zero N, or it does not affect the braking force and operability. Further, even in the structure of the first embodiment, it is possible to use the bolt 25 by removing it.

Although the embodiments of the brake device for an air hoist according to the present invention have been described above with reference to the drawings, the present invention should not be interpreted as being limited to the above-mentioned embodiments, and may be modified as appropriate without prejudice to the above embodiments. Of course, changes and improvements are possible.

[Effects of the Invention] As described above, according to the present invention, the load on the first splinter 22 that urges the pressing body 20 can be reduced with a simple and inexpensive structure, and the air hoist can be started at low speed and at high speed. It is possible to stably change the speed from low speed to low speed.

That is, since the piston 21 moves independently in the axial direction separately from the pressing body 20, the pressing body 20 is not directly affected by back pressure and requires the load of the first spring 22 that biases the pressing body 20. It can be reduced to a minimum and the braking force can be adjusted to the appropriate level.

Furthermore, as shown in FIGS. 3 and 4, the above-mentioned braking force adjustment device is capable of adjusting the braking force by linking the change in the braking force with the change in air pressure with the amount of movement of the piston 21. If the hoist is operated to start at a low speed, it is possible to limit the rapid increase.
Even if the piston 21 responds instantaneously due to air pressure fluctuations, the first spring 22 that biases the pressing body 20 will be delayed by a small amount of time relative to the movement of the piston 21.
The fine movements of the piston 21 are not directly transmitted to the pressing body 20, so that fluctuations in brake braking force are kept small, and vibrations of the hoist and the suspended load can be suppressed without being affected much by fluctuations in air pressure. Furthermore, even when an operation is performed to change the speed from high speed to low speed, the piston 21 instantly responds to the decrease in air pressure, or the first spring 22 acts as a buffer. As a result, a sudden increase in braking force is suppressed, and the influence of air pressure fluctuations is small, making it easy to obtain subtle braking forces and making stable speed changes possible.

By making it possible to more delicately control the flow rate of the main control valve 11 through this modification, the operability of the hoist can be further improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment of a brake device for an air hoist according to the present invention, FIG. 2 is an elevational view of an air hoist according to the present invention, and FIG. 3 is a diagram showing a brake device according to the present invention. FIG. 4(a) is a diagram showing the relationship between air pressure, flake braking torque, and motor output torque of a conventional brake device, and FIG. FIG. 4(b) is a diagram showing the relationship between the piston movement amount, flake braking torque, and motor output torque of the conventional air hoist brake device, and FIG. 5 is a diagram showing the relationship between the brake device of the air hoist according to the present invention. A vertical cross-sectional view of a second embodiment of the device. FIG. 6 is a vertical cross-sectional view of a conventional air hoist brake device. 7 and 8 are air supply circuit diagrams of a conventional air hoist, and FIG. 9 is an explanatory diagram of a vane type air motor. [Description of symbols of main parts] 2...Brake plate 9...Second spring 20...Press body 21...Piston 22...First Spring A... Air chamber Figure 1 Figure 3 □ Air pressure Mρa Figure 5 4

Claims (1)

[Claims] 1. A reversible rotational drive source, a housing, a rotating shaft supported by the housing and rotated by the reversible rotational drive source, a transmission device that reduces rotation of the rotating shaft, and a load. A chain gear that supports a chain having a hanging hook and is rotated by the transmission device, a brake shoe fixed to the housing, a brake plate attached to the rotating shaft, and a brake plate pressed against the brake shoe. a pressing body that brakes the rotation of the rotating shaft by frictional force; a piston that is movable in a direction of pressing the pressing body and a direction of releasing the pressing; and a piston that is disposed between the pressing body and the piston, An air hoist comprising an elastic means that gradually loosens the pressing force of the pressing body when the air hoist moves in the direction of releasing the pressing force. 2. A reversible rotary drive source powered by compressed air, a housing, a rotating shaft supported by the housing and rotated by the reversible rotary drive source, a transmission device that decelerates the rotation of the rotating shaft, and cargo. a chain gear that supports a chain having a hook suspending the chain gear and is rotated by the transmission device; a brake shoe fixed to the housing; a brake plate attached to the rotating shaft; and a brake plate attached to the brake shoe. a pressing body that presses and brakes the rotation of the rotating shaft by frictional force; a piston that is movable in a direction of pressing the pressing body and a direction of releasing the pressing; and a piston that is disposed between the pressing body and the piston and that presses the a first spring that biases the body to press the brake plate; a variable pressure air chamber that applies pressure to the piston and moves the piston in a direction that reduces the biasing force of the first spring; and a second spring that urges the piston to move in a direction that increases the biasing force of the first spring, and when the pressure in the air chamber is low, the second spring moves the piston to move the piston toward the first spring. Since the biasing force of the spring is increased, the rotation of the rotating shaft is braked by the pressing force of the pressing body pressing the brake plate, and on the other hand, as the pressure of the air chamber increases, the pressure of the air chamber increases. The pressure moves the piston against the biasing force of the second spring, causing the first
An air hoist characterized in that the urging force of the spring is reduced, thereby weakening the pressing force with which the pressing body presses the brake plate and allowing rotation of the rotating shaft. 3. The air hoist according to claim 1 or 2, wherein the brake plate is attached to the rotating shaft so as to be movable in the axial direction, and rotates together with the rotating shaft.